September 12, 1918 : U.S. launches Saint-Mihiel offensive

Introduction

On this day in 1918, the American Expeditionary Force (AEF) under the command of General John J. Pershing launches its first major offensive operation as an independent army during World War I.

After lending much-needed support to the exhausted French forces at Belleau Wood in June 1918 and in the Second Battle of the Marne in July, Pershing and Allied Supreme Commander Ferdinand Foch decided that the 1st Army of the AEF should establish its headquarters in the Saint-Mihiel sector and prepare a front facing the Saint-Mihiel salient, a triangular wedge of land between Verdun and Nancy, in northeastern France, that had been occupied by the Germans since the fall of 1914. By heavily fortifying the area, the Germans had effectively blocked all rail transport between Paris and the Eastern Front. In mid-August, the AEF was given the task of leading an attack on the salient; it would be its first independent operation of the war.

The attack began on September 12, 1918, with the advance of Allied tanks across the trenches at Saint-Mihiel, followed closely by the AEF’s infantry troops. Foul weather plagued the offensive as much as the enemy troops, as the trenches filled with water and the fields turned to mud, bogging down many of the tanks. Despite the conditions, the attack proved successful—in part because the German command made the decision to abandon the salient—and greatly lifted the morale and confidence of Pershing’s young army. By September 16, 1918, Saint-Mihiel and the surrounding area were free of German occupation. The American forces immediately shifted further south, to a new offensive near the Argonne Forest and the Meuse River, where they combined with British and French forces to further hammer the Germans, as the Allies moved ever closer to victory in World War I.